This invention relates to a hand-held speed and range detector. More particularly, the present invention relates to a detector utilizing a laser beam capable of being reflected from the surface of a target and which is aimed through the use of a sight that allows simultaneous viewing of the target and the determined velocity or range of the target.
In the field of traffic speed enforcement, two methods of detecting vehicle speed have generally been utilized. The first in use was instrumentation to calculate an average speed between two points by measuring the elapsed time in traversing the predetermined distance. The second method utilizes the doppler effect in radar systems to measure the frequency difference between transmitted and reflected microwave energy.
The first of these systems, the distance/time calculation method involves the inconvenience of determining a distance on the roadway which is then entered into a calculation system in order to determine the speed of the vehicle. Such a procedure is time consuming and inconvenient and eliminates mobility on the part of the traffic officer. In addition, the large measured distance may permit the driver of the target vehicle to modify his speed prior to completion of the measured distance and thereby escape detection. Finally, as the time measurement is often manually started and stopped by the operator the element of human error is added into the accuracy of the speed determination.
The identification of speeding vehicles has long relied upon the use of high frequency radio waves reflected from the surfaces of vehicles to allow a determination of vehicle velocity. While the use of conventional radar systems overcomes the deficiencies of the distance/time method of speed detection, they introduce another set of problems to the determination. The first problem is that the effective beam width of most microwave traffic radar is between 12 and 18 degrees. This wide beam angle covers several lanes of a roadway at the usual operating distances and results in the inability of the radar beam alone to differentiate between individual lanes of traffic and vehicles therein. Also, other objects in the path of the radar beam may reflect the radar energy and provide an inaccurate speed determination of the target vehicle. Therefore, the operator must be able to visually observe the surroundings of the target vehicle during the speed measurement so the operator is able to assert that the surroundings did not interfere with the speed measurement. This contemporaneous awareness of the surrounding environment is denominated as "tracking history" within the art and is required for judicial acceptance of a radar reading as vehicle speed evidence.
A second difficulty presented by the use of conventional microwave traffic radar is the ease with which the radar signal may be detected by radar receiving units in a motorist's vehicle. The proliferation of such "radar detectors" in recent years has allowed many violators to successfully avoid detection.
While the use of laser transmissions for speed detection has been set forth, for example, in U.S. Pat. No. 3,373,441, the device described therein suffers from several difficulties. For example, the device described requires the operator to sight through a viewing tube with the head down.
In addition, the operator's view of the area surrounding the vehicle is obscured by the device during the period of measurement. Therefore, the operator is unable to provide the required "tracking history" to a court for judicial acceptance of the detected speed.
Furthermore, outside the field of traffic speed enforcement, there is a need for a hand-held range detector that may be conveniently and rapidly aimed at small targets such as moving game, small watercraft and the like. In such applications the operator wishes to know the exact distance to the target with the assurance that the target itself, and no an adjacent object or background, is being sensed and measured.
It is, therefore, a general object of the present invention to provide a hand-held laser detection device having pinpoint aiming capability so that the device will not be influenced by the target's surroundings, in order that a rapid and accurate determination of the speed or range of the target may be made.
With respect to traffic speed enforcement, it is an object of the present invention to provide a laser speed detection device which allows the operator to develop a tracking history of the subject vehicle.
It is a further object of the invention to provide a speed or range detector which permits the operator to observe the detected speed or range of the target without diverting his vision from the target.
It is another object of the present invention to provide a speed or range detection device which allows the operator to observe the detected speed or range reading without the need to refocus his eyesight to a second focal point to make such a reading.
Another object of the present invention is to provide a speed or range detection device which will present no parallax as the operator changes head positions with respect to the detection device.
A further object of the present invention is to provide a sight or aiming apparatus for a speed or range detection device which allows the operator to maintain his head in an upright position while simultaneously observing the target and the detected speed or range of the target.
Another object of the present invention is to provide a speed or range detection device which is relatively compact so as to enable it to be easily handled and aimed by an operator.
Another object of the present invention is to provide a laser speed or range detection device having a laser energy transmitting pathway and laser energy reception pathway which are coaxial and concentric.
It is still another object of the present invention to provide a sight for a speed or range detection device which continuously displays the detected velocity or range of the target on the sight.
It is yet another object of the present invention to provide a display showing the detected velocity or range of a target with the display having a relatively short optical path from the sight mechanism of the detector.
Furthermore, it is an object of the present invention to provide a display of the detected speed or range of the target by projection of the determined speed o range along an optical path having an effective focal length substantially greater than the length of the optical path.
The above and further objects and novel features of the invention will more fully appear from the following description when the same is read in conjunction with the accompanying drawings.